Study of the chemical constituents of ethanol extract from the aerial parts of Atalantia buxifolia led to the identification of a new acridone alkaloid named as buxifoliadine (1), along with known compounds citrusinine--I (2), N-methylatalaphylline (3), Severinolid (4) and cycloseverinolide (5). Structural elucidation of compound 1 was carried out by a combination of mass spectrometry and (1)H and (13)C NMR spectroscopy analyses.